package com.atnjupt.java1;

/**
 * 使用同步机制将单例模式中的懒汉式改写为线程安全的
 *
 * @author Wizarder
 * @create 2021-02-18 20:33
 */
public class BankTest {
}

class Bank {
    private Bank() {

    }

    private static Bank instance = null;

    public static Bank getInstance() {
//        方式一
//        synchronized (Bank.class) {
//            if (instance == null) {
//               instance =  new Bank();
//            }
//            return instance;
//        }
        //方式二：效率更高
        if (instance == null) {
            synchronized (Bank.class) {
                if (instance == null) {
                    return new Bank();
                }
            }
        }
        return instance;
    }
}